Directive sending system.



O. E. BUCKLEY.

DIRECTIVE SENDING SYSTEM.

APPUCATUN FRED SEPT. 13. 1911- Patent-ed Apr. 22, 1919.

is 5 w? M. im S s g M d- I I I F 3 /0 l0 MII I P l0 l0 UNITED STATES PATENT OFFICE.

OLIVER E. BUCKLEY, OF EAST ORANGE, NEW JERSEY, ASSIGNOR, BY MESNE ASSIGN- MENTS, TO WESTERN ELECTRIC COMPANY, INCORPORATED, A CORPORATION OF NEW YORK.

DIRECTIVE SENDING SYSTEM.

Application filed September 13, 1915.

" o (M whom it may concern Be it known that I, OLIVER ELLSWORTH BUcKLnY, a citizen of the United States, residing at East Orange, in the county of Essex and State of New Jersey, have invented cer tain new and useful Improvements in Directive Sending Systems, of which the following is a full, clear, concise, and exact de scription.

This invention relates to the art of transmitting signals through space by means of electromagnetic waves.

Its object is to secure a flow of radiant energy from the transmitting station principally in certain definite directions. This object is accomplished by making use or the fact that a number of sources of wave radiation, spaced equally along a line and all oscillating with the same constant frequency, tend to produce by interference a flow of energy principally in one or more definite directions. The power radiated, instead of being approximately uniformly distributed in direction, as in the case-of a single source of radiation, will he concentrated in certain definite directions. For exam is, consider a number of antennae each capa le of radiating waves of a given wave length, uniformly spaced along a straight line and all emitting radiation exactly in synchronism and in phase. Suppose first that the distance between successive antennae is equal to the wave length. Then a wave starting from one antenna will reach its nearest neighbor just as a wave is starting from that neighbor, so that the two will agree in phase and combine to produce double the eii'ect of either; moreover, at every point along the above mentioned line, extended, the waves from every antenna will a e in phase, and consequently all alon t is line the amplitude and the energy of t e radiation will be maxi mum. On the other hand, other straight lines drawn outward from the antenna system will in general not be so favorably located, and waves arriving at a given point of such another line from the several antennae will not agree in phase and will tend to cancel one another. The maximum flow of energy will, therefore, be confined to a few special directions. It is not necessary that the distance between successive antennae be exactly a wave length; if it is difi'erent Specification of Letters Patent.

Patented Apr. 22, 1919.

Serial No. 50,463.

from that, however, the direction of maximum energy flow will change and, in fact, the direction of this flow may be adjusted by changing the frequency and consequently the wave length of the emitted radiation. It is, however, necessary that the mutual distances be comparable with the wave length by which is meant, in this specification, that these distances should not be less than perhaps one-tenth the wave length and not more than ten times as large. It is also necessary, in order to secure this effect of directional sending, that the oscillations in the various antennae shall be exactly in synchronism and that their phase relations shall be invariable. These requirements are usually summarized in the statement that the several sources shall be coherent.

A particular object of this invention is to insure that the radiating antennae shall be coherent and to obtain this coherence in a practical way by controlling their oscillati ons from a single low-power source.

In order that the novelty of this invention may be appreciated, it is necessary to point out that a number of inde endent oscillating antennae, not controlled rom one source of power and not otherwise connected with one another, cannot be maintained in synohronism and in phase. Further, it is not practically possible to suppl with power from one central source a num r of antenna: separated by the distances here contemplated for that would involve transmission of high frequency power of large amount over a distance of several miles. Aside from the loss in transmission over such distances, the mutual capacity of the line wires and their other constants would make it impossible to tune the system sharply to the high {afrequency desired for radiation. In this invention these difiiculties are overcome by locating a power-supplying amplifier at each an tenna, all the power to be radiated being derived from its output circuit, and then con trolling the operation of these amplifiers from a source of low power oscillations modulated in accordance with the message wave to be sent and centrally located with respect to the several antennae. In this way the characteristics of the lines from the central source to each antenna have not the same deleterious effect upon the radiation omitted from the antennae, for a low efficiency in the transmission of such small amounts of power is not objectionable.

The circuit arrangement of this invention is shown in the drawing. Here 1 represents a generator of high frequency low power oscillations which is shown as an oscillating amplifier of the audion type. Such an amplifier, having its input circuit and its output circuit inductively connected, will oscillate at a frequency determined by the constants of the circuit. In its place, however, any suitable generator of sustained high frequency waves may be used. Transformer 2 connects this generator to the input circuit of the thermionic amplifier 3; into this same circuit are introduced also, by transformer U, the low frequency oscillations due to variations in resistance of microphone 4 energized by battery 5. The low frequency voltage thus applied to 3 is higher than the high frequency voltage, and its effect is to change the amplifyin power of the amplifier 3 so that the high frequency oscillations, appearing in the output circuit of the latter, are modulated in accordance with the low fre quency oscillation. This method of modulating high frequency oscillations has been disclosed by van der Bijl in his United States application, Serial No. 46,6i3, dated August 21, 1915.

By means of transformer 7 the modulated high frequency low power oscillations in the output circuit of 3 are transmitted to a line leading to the various antennae. The transformers 8 impress these oscillations upon the input circuits of amplifiers 9, which in turn impress the amplified oscillations upon the terminals of the high power amplifiers 10. It will usually be necessary to employ a number of these amplifiers arranged in parallel as shown. (Am lifiers of this type are connected in parallel y connecting together all the filaments, all the grids and all the plates.) The batteries 12 su ply direct current to the output circuits of the amplifiers 9, and the choke coils 11 are provided to allow this flow of direct current Without alfording paths for the high frequency oscillations. The amplifiers energize the twocircuits 13, 14, the inductance coils of which are coupled to the coils 15 in antennae 16. By this arrangement the oscillations in the several antennae are maintained in exact gynpihronism and their phase relations are Throughout this specification the use of the Word synchronism implies agreement with, respect to frequency, but not nccessaw ril y with respect to phase of two oscillations of similar wave forms.

I wish to point out explicitly that the object of the control circuit is to secure fixed phase relations among the oscillations, but that these need not, and in eneral will not, be in the same phase; also tiat the antennae need not be equally spaced, since the phase of the oscillation in any antenna may be adjusted by any of a number of methods well known to engineers and others familiar with the properties of alternating currents.

' hat is claimed is:

1. In a system for radio transmission, a plurality of sending antennae, power-supplying amplifiers associated with each. of said antenna, and a common low power means for controlling the operation of said amplifiers.

In a system for radio communication, a plurality of sending antennae, successive antemiae being separated by a distance suitable for obtaining directive sending, a power supplying amplifier of the unilateral type associated with each of said antennae, and a central source of low power modulated high frequency oscillations connected with said amplifiers and controlling their operation.

3. In a system for radio transmission, a plurality of sending antennae, a source of low power high frequency oscillations, means for modulating said high frequency oscillations in accordance with the signals to be transmitted, thermionic amplifiers associated with each of said antennae, means for impressing the low power high frequency oscil lations upon the input circuits of said amplifiers, and means for impressing the resultant high power oscillations upon said antennae.

4. In a plurality sending antennae, a source of low power high frequency oscillations, a circuit containing a telephone transmitter and a source of current therefor, means for modulating said high frequency oscillations in accordance with the oscillations in said circuit, thermionic amplifiers associated with each of said antennae, means for conductively transmittin said low power oscillations to said amp ifiers, and means for impressing the resultant high power oscillations upon said antennae. 7

In witness whereof, I hereunto subscribe my name this 10th day of September A. D., 1915.

OLIVER E. BUCKLEY.

Copies of this patent may be obtained for five cents each, by addressing the "Commissioner of Patents,

" Washington, D. 0."

system for radio transmission, a. o 

